Method and apparatus for vertical casting of hollow metalic bodies



Aug. 30, 1966 L. BABEL ETAL 3,268,959 METHOD AND APPARATUS FOR VERTICAL CASTING OF v HOLLOW METALIC BODIES Filed April 15, 1963 2 Sheets-Sheet 1 FIG. 1

FIGS

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METHOD AND APPARATUS FOR VERTICAL CASTING 0F HOLLOW METALIC BODIES 2 Sheets-Sheet 2 Filed April 15, 1963 United States Patent 3 268 959 Mnrnon AND arrhnirrrrs non visnrrcar. CASTING 0F HOLLUW METALIQ BQDIES lLouis Babel, Sauvigny-les-Eois, Nievre, and Pierre Peytavin, Aulnoye Ayrneries, Nerd, France, assignors to Socit (Iivile dite: Socit Civile dEtuties tie Centrifugation, Paris, France, a corporation of France Filed Apr. 15, 1963, Ser. No. 273,0ti Claims priority, application France, Apr. 26, 1 .962, 895,753, Patent 1,329,048 Claims. (Cl. 22-573) Several different kinds of apparatus have already been designed for carrying out the vertical continuous casting of metalic hollow bodies.

On the one hand, casting has been carried out in a rotating mould without using an internal mandrel, the formation of the hollow body being due solely to the action of centrifugal force.

Apparatus have also been provided which comprise a rotating internal mandrel which may be given a to and fro motion, this mandrel effecting the formation of the inner part of the casting during manufacture.

The present invention is concerned with a method and an apparatus belonging to the latter type.

The method according to the invention makes it possible to obviate the disadvantages which have been encountered hitherto and which have been due mainly either to the locking of the mandrel in the casting or to irregularities in the formation of the inner part of the casting.

The present invention relates to a novel method for effecting the vertical continuous casting of metalic hollow bodies, this method being essentially characterized in that the workpiece is cast in a rotating mould within which is situated a rotating mandrel having a downwardly directed conicity, the axis of this mandrel being slightly eccentric with respect to the axis of the rotating mould, the jet of liquid met-a1 falling on to the casting at a point offset by to 120 approximately upstream (relatively to the direction of rotation of the mandrel and of the casting) of the point of the mould nearest the mandrel According to the invention, it is preferable to make the conical mandrel of such a construction that it can be cooled by internal circulation of water. Furthermore, the mould is advantageously cooled by a similar circulation.

In one particular embodiment of the apparatus for carrying out the method according to the invention, the rotating mandrel is supported by two bearings carried by two eccentric sleeves mounted in one another and adapted to be displaced independently of one another in such a manner as to vary both the value of the eccentricity of the axis of the mandrel relatively to the mould axis, and the direction of this eccentricity.

In order to enable the invention to be more easily understood, a description will now be given, purely by way of example, of one embodiment which is illustrated in the accompanying drawings, wherein:

FIGURE 1 is a diagrammatic plan View illustrating the basic idea of the method according to the invention;

FIGURE 2 is a diagrammatic vertical sectional view of an apparatus for carrying the method into effect;

FIGURE 3 is a sectional view taken along the line III-4H of FIGURE 2.

In FIGURE 1, which represents diagrammatically a horizontal sectional view of the apparatus in a plane situated slightly above the spout through which the liquid metal is fed, reference numeral 1 designates the mould which is driven rotationally in the direction of the arrow F about its axis 0, and 2 is the mandrel which according to the invention is also driven in rotational movement in the direction of the arrow F about its own axis 0' In order to facilitate the understanding of the drawings, a considerable amount of eccentricity O-O' has 3,2683% Patented August 30, l fid been shown in this drawing but, as will be seen hereinafter, this eccentricity is in practice much less than what is represented in the drawing.

I designates the point of impact of the jet of liquid metal on the casting 3 and the drawing clearly shows the angle as which, according to the invention, should have a value of between 30 and It will be already appreciated, by means of the diagrammatic View shown in FIGURE 1, that the upper portion of the casting is solidified in a Zone adjacent the points A, A, and then is released by the mandrel until it receives a fresh charge of metal when passing below the point I.

It will also be appreciated that the method according to the invention, owing to the eccentricity of the mandrel relatively to the mould, eliminates substantially all risk of jamming the mandrel in the casting and nevertheless ensures very satisfactory formation of the inner portion of the casting owing to the fact that over a considerable path of travel about the points A, A, the casting, still in the liquid or pasty state, is held supported between two walls which are substantially parallel and are moving in the same direction.

In FIGURE 2, reference numeral 11 again indicates the mould which is driven in rotational movement about its axis 0 and the structure of which is such that it can be cooled by means of a fluid entering through the duct 4 and projected onto the mould through appropriate orifices.

In order to simplify the drawings, the means whereby the mould is driven in rotational movement have not been illustrated.

FIGURE 2 also shows the mandrel 2 rotating about its axis 0, the lower portion 5 of the said mandrel according to the invention having a slight downwardly directed conicity.

The inner mandrel 2 is cooled by the introduction of water circulating at a considerable speed, which enters through the tube 6 and leaves at 7, as indicated by the arrows in the figure.

The mandrel 2 is supported by two upper and lower radial bearings 8 and 8.

The outer portion of the bearing 8 (FIGURE 2) is supported by a sleeve 9 capable of being rotated within a sleeve It) by means of peripheral teeth 11 driven by a worm 12. The sleeve ltl is itself adapted to be rotated within the frame 13 of the apparatus by means of peripheral teeth 14 driven by a worm 15.

The eccentricity of the mandrel 2 relatively to the sleeve 9 being equal to the eccentricity of the sleeve 9 relatively to the sleeve 10, it will be appreciated that, by acting on the worm 12, it is possible to vary the eccentricity of the mandrel 2 relatively to the sleeve 16) between zero and a maximum value.

Since, by construction, the sleeve It) is capable of being displaced in rotational movement on an axis identical with the axis of rotation of the mould 1, it will also be appreciated that it is possible to vary the angular orientation of the eccentricity of the mandrel 2 relatively to the mould 1 by acting on the hand wheel 16 connected to the worm 15.

It will be seen, therefore, that the apparatus according to the invention permits of great flexibility in the regulation of the position of the mandrel relatively to the mould.

As FIGURE 2 shows, the mandrel is rotated by means of the motor 17 fixed to a cage 18 which is itself mounted on the upper portion of the mandrel 2 by means of radial bearings 19, and rotational movement of which is prevented by any desired means.

'By means of a pinion 20 the motor 17 directly drives a toothed annulus 21 fast with the upper portion of the mandrel.

Examples will now be given of the adjustment of the aforesaid apparatus in order to carry the method according to the invention into effect.

Experiments were carried out by the applicants with a machine equipped with a copper mould 195 mm. in internal diameter and 450 mm. in height, and with a mandrel having a diameter of 120 mm. and a length in the vicinity of the length of the mould; the mould exhibited a negative taper i.e. a constriction in the downward direction corresponding to a 1% reduction in diameter. Under these conditions they were able first of all to establish a rule from which it can be said that the product of the speed of extraction of the casting by the total conicity of the lower end of the mandrel should be substantially invariable in order to ensure the success of the operation, this product having generally a value between 6 and 10.

The total conicity of the mandrel is understood to be the ratio between the variation of the diameter measured between two given points on the axis of the mandrel, and the distance of these two points from the axis of the mandrel.

Thus for a conicity of 8% a displacement of 1000 millimeters along the length of the mandrel corresponds to a variation of diameter of the mandrel of 8 mm., or again, a displacement of 100 millimeters along the length of the mandrel corresponds to a variation of diameter of the same of 0.8 mm.

Thus, in the case of a semi-hard steel, good results are obtained with a product value in the vicinity of '8. The applicants have obtained satisfactory results with an extraction speed of 1 metre per minute, and a total conicity of the mandrel equal to 8%. In the case of a non-rusting steel of the 18/8 type having 3% molybdenum, satisfactory results were also obtained with the same rule.

The value of the eccentricity represented by the distance O-O in FIGURE 1 is generally between 0.4 and 2.5 mm.

The speed of extraction of the casting varies between 50 cm. and 2 metres per minute, whereas the rotational speed of the mould is generally between 60 and 200 rpm.

As indicated hereinbefore, the angle or formed by the jet impact point I relatively to the point A on the mould, at which the mandrel is nearest to it, is generally, according to the invention, between 30 and 120 and preferably in the vicinity of 90.

By way of example, according to the invention a casting of semi-hard steel is continuously cast with an external diameter of 190 mm. and an internal diameter of 120 mm., with an extraction speed of 1 metre per minute, regulating the apparatus in such a manner that the on angle is about 90, the eccentricity OO' being 0.4 mm., the rotational speed of the mandrel 150 revolutions per minute, and the total conicity of the mandrel 8% It will be understood that the embodiment of the invention which has been described hereinbefore is not intended to have any limitative character, and may be modified in any desirable way without thereby departing from the scope of the invention.

What is claimed is:

1. Apparatus for casting metal comprising a mandrel mounted to rotate about a vertical axis, a hollow mould encircling said mandrel and mounted to rotate about an axis parallel to but slightly spaced from the axis of said mandrel so that the inner wall of the mould approaches the outer wall of said mandrel more closely at one point. on its periphery than elsewhere, and means for supplying molten metal to said mould at an angular distance of between 30 and 120 from said one point preceding the point at which the mandrel and mould are closest.

2. Apparatus as claimed in claim 1 in which said angular distance is approximately 3. Apparatus as claimed in claim :1 in which the distance between said axes is between 0.4 and 2.5 mm.

4. Apparatus as claimed in claim 1 in which said mandrel tapers inwardly as it approaches its lower end.

5. Apparatus as claimed in claim 1 comprising means for adjusting the distance between said axes.

6. Apparatus as claimed in claim 1 in which said mandrel comprises an outer sleeve having within it an eccentrically mounted inner sleeve, and an inner mandrel member rotatably mounted in said inner sleeve, said mandrel having a cylindrical outer surface and an inner core positioned eccentrically with respect to said outer sleeve which surrounds said mandrel, so that rotation of said inner sleeve within the bore of said outer sleeve causes the axis of said inner sleeve to shift relative to that of said mandrel.

7. The method of making hollow castings by vertical continuous casting comprising the steps of rotating a first cylindrical surface within a second cylindrical surface about an axis displaced from but parallel to that of said second cylindrical surface so that said surfaces approach each other most closely at one particular position and feeding molten metal between said surfaces at a feeding position reached by any given point on one of said surfaces between 30 and before it reaches said particular position.

8. The method claimed in claim 7 according to which said feeding position is reached by any given point on one of said surfaces 90 before it reaches said particular position.

9. The method claimed in claim 8 according to which said surfaces are rotated about axes spaced from each other by a distance equal to from 0.4 to 2.5 mm.

10. The method claimed in claim 9 according to which the product of total conicity of the mandrel and the speed of extraction of the casting from the mould in terms of millimeters per minute is between 6 and 10.

References Cited by the Examiner UNITED STATES PATENTS 2,752,648 7/ 1956 Robert 22-57.3

FOREIGN PATENTS 1,253,308 1/1961 France. 1,136,797 9/ 1962 Germany.

538,810 3/ 1942 Great Britain.

I. SPENCER OVERHOLSER, Primary Examiner.

MARCUS U. LYONS, Examiner.

R. A. SANDLER, Assistant Examiner. 

1. APPARATUS FOR CASTING METAL COMPRISING A MANDREL MOUNTED TO ROTATE ABOUT A VERTICAL AXIS, A HOLLOW MOULD ENCIRCLING SAID MANDREL AND MOUNTED TO ROTATE ABOUT AN AXIS PARALLEL TO BUT SLIGHTLY SPACED FROM THE AXIS OF SAID MANDREL SO THAT THE INNER WALL OF THE MOULD APPROACHES THE OUTER WALL OF SAID MANDREL MORE CLOSELY AT ONE POINT ON ITS PERIPHERY THAN ELSEWHERE, AND MEANS FOR SUPPLYING MOLTEN METAL TO SAID MOULD AT AN ANGULAR DISTANCE OF BETWEEN 30 AND 120* FROM SAID ONE POINT PRECEDING THE POINT AT WHICH THE MANDREL AND MOULD ARE CLOSET.
 7. THE METHOD OF MAKING HOLLOW CASTINGS BY VERTICAL CONTINUOUS CASTING COMPRISING THE STEPS OF ROTATING A FIRST CYLINDRICAL SURFACE WITHIN A SECOND CYLINDRICAL SURFACE ABOUT AN AXIS DISPLACED FROM BUT PARALLEL TO THAT OF SAID SECOND CYLINDRICAL SURFACE SO THAT SAID SURFACES APPROACH EACH OTHER MOST CLOSELY AT ONE PARTICULAR POSITION AND 